PROJECT SUMMARY/ABSTRACT Attention-deficit/hyperactivity disorder (ADHD) is a developmental risk-factor for alcohol-related problems and disorders. Co-occurring ADHD and alcohol problems are associated with long-term morbidity, disability, and poor treatment prognosis, posing high direct and indirect costs to these individuals and society. College is a period during which youth with ADHD are especially vulnerable for the escalation of risky alcohol use, yet key psychological, behavioral, and environmental factors that amplify risk during this critical developmental period are largely unexamined. The proposed study seeks to integrate foundational components of behavioral economics (BE) models of addiction and novel daily diary methodology, with the goal to elucidate predictors and moderators of alcohol problems among college students with and without ADHD. Our first aim is to simultaneously evaluate baseline differences in multiple BE risk factors (i.e., delay discounting, alcohol demand, substance-free reinforcement) among college students with and without ADHD. We hypothesize that students with ADHD will display more delay discounting, evidence more alcohol demand, and report less substance-free reinforcement relative to their typically-developing peers. We also propose to explore the independent and interactive effects of baseline BE risk factors and ADHD on the daily patterns of drinking behaviors, alcohol-related negative consequences, and substance-free reinforcement across 14 days using daily diary methodology. We hypothesize that both baseline BE risk factors and ADHD will independently predict riskier drinking behaviors, more negative consequences of drinking, and less daily engagement in valued substance-free alternatives. Further, the association between ADHD and these outcomes will be strongest for students with more baseline BE risk factors, relative to students with either ADHD or baseline BE risks alone. Through the proposed research project and the larger agenda of the training plan, this fellowship will provide me with all of the foundational skills to launch an independent program of research elucidating BE risk for alcohol-related problems among high-risk youth.